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Playful Puppy Robot 



i 



Make Projects 



build, hack, tweak, share, discover, J 



Playful Puppy Robot 



Written By: OddBot 



f TOOLS: 

• #1 Phillips Screwdriver (1) 

• Hot glue gun (1) 

• Needle Nose Pliers (1) 

• Small Flathead Screwdriver (1) 



© PARTS: 

Quad Bot robot chassis (1) 
Pan /Tilt kit (1) 
IR Compound Eye (1) 
Magician Robot Controller (1) 
Jumper Wire Pack (1) 
Servo extension cable (4) 
Cable ties (10+) 
Li-Po battery pack (1) 
Spacers (2) 
Spacers (4) 



SUMMARY 



This guide will show you how to build a playful puppy robot that can be programmed with the 
Arduino IDE. Sample code is provided that will let you control the robot with simple hand 
gestures to perform tricks such as shaking hands and walking on his back legs. 

The robot is relatively simple to build and is made from robot parts and accessories 
available in many online robot shops. You only need a couple of screwdrivers and some 
pliers. No soldering is required! 



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Playful Puppy Robot 



You can download the instruction manuals for the Quad Bot chassis and the Magician 
controller here . 

This project works best with a LiPo battery but can be built using six NiMH AA batteries if 
required. When you download the sample code choose the code that suits your battery type 
as the balance is a little different when the robot stands on its back legs. 



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Playful Puppy Robot 





STOP 
in center 
position 



Servo 

output 

shaft 






A PDF of the Quad Bot instruction manual can be downloaded from the DAGU products 
support site . Begin by checking that all your servos are centered. When you look through 
the clear housing above the cable you should see a stop on the output gear. This stop 
should be central so that the servo can rotate 90 degrees in either direction. 

Mount the foam rubber feet as shown in the instruction manual onto 4 of the 8 leg 
segments. All leg segments are identical so it does not matter which 4 you choose. 

Mount a miniature servo on each of the 4 leg segments that you put a foot on. Make sure 
the servo output shaft is away from the foot as shown. These are your "Knee" servos. 

Now take the 4 remaining leg segments and mount servo horns as shown. These leg 
segments can now be mounted on the servos as shown. The leg should be able to 
straighten out or fold up. If not then remount the segment. 

You should now have 4 identical legs. We need to make 2 of them "Left" legs and the other 
2 will be "Right" legs. The only difference is how we mount the "Hip" servo. Note which 
side the servo output shaft is on. 

Next we need to mount the 4 round servo horns onto the Quad Bot chassis. Do not mount 
them as shown in the instructions. Mount them closer to the end of the mounting plate as 
shown in the third photo to make more room for your battery. 

Mount your 4 legs. Note that the rounded end will be the back and has a hole in the center 
so you can mount a tail if you wish. Connect the 4 servo extension cables to the front leg 
servos. 



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Playful Puppy Robot 









Eye connections 



1 r +5V 

2. Top 

3. Left 

4. Bottom 

5. Right 

6. IR LED5 
T.OV 





Align your servos as shown in step 1 and assemble the kit according to the instructions. 
This kit was originally designed here . 

Mount your compound eye with the brass spacers provided so that the wires come out at 
the bottom. 

If possible use female-to-female jumper wires at least 150mm (6 inches) long to connect 
your eye to the controller. In my case I used a female-to-female connected to a male-to 
male-jumper wire. As the Magician controller has both male and female headers on the I/O 
pins it doesn't matter too much what wires you use. 



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Playful Puppy Robot 





• I used a couple of 25mm (1 inch) 
hex brass spacers to mount my 
pan/tilt assembly. The pan/tilt 
assembly is then fitted to the Quad 
Bot mounting plate using a couple 
of pan-head screws. If you don't 
have pan-heads then use normal 
screws with washers. 

• I have mounted my assembly a 
reasonable way back to improve 
the robot's balance and to reduce 
the chance of the pan and tilt 
servos being damaged as a result 
of the head hitting walls or 
furniture. If you change this then 
the robot may not be able to stand 
on his back legs. 



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Playful Puppy Robot 







• I have previously tried making this robot with NiMH batteries. Because of the current draw 
I found that AA batteries were required and that they were a bit too heavy. The robot 
worked OK but it could not stand on its back legs. You just can't beat LiPo batteries for 
power/weight ratio. 

• Your battery needs to be not much bigger than 50mm x 60mm; otherwise it will restrict leg 
movement. 

• Cable-tie your battery in place with your wires coming out on the right-hand side, 
remembering that the curved end is the back. Make sure your battery will not obstruct the 
legs. Do not overtighten the cable ties. If your battery tends to slip out then use a small 
piece of double-sided tape between the battery and the mounting plate. 

• While you have the cable ties out, now is a good time to tidy up the servo cables. Make 
sure the servo movement is not restricted. 

• LiPo batteries are great but can catch fire or explode if mistreated. Do not use a 
battery that shows any signs of damage or swelling. Do not allow the battery 
voltage to fall below 6V otherwise damage can occur. Use a suitable LiPo charger and be 
careful not to overcharge your battery. When charging your battery keep it away from 
flammable liquids and objects. 

• If you do not have a suitable LiPo battery or do not feel comfortable using them then use 
6x NiMH AA rechargeable batteries. A 2x3 battery holder will fit but the weight is greater 
so the robot cannot stand on its back legs. 




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Playful Puppy Robot 




Servo 

power Digital; Servo 



Lsft 
motor 
SOOmA 




USB 

interface 



Reset 

button 

013 LED 
Power LED 



AQ-A5 
+SV (Vcc) 

cv (Grid) 



Reverse polarity 

protection diode 



5V 
regulator 



Analog 
impute 




• The Magician robot controller is ideal for this project because of its low cost and that fact 
that it can drive both servos and DC motors without additional shields. 

• You can download the Magician controller instruction manual from the DAGU products 
support site . 

• Mount the controller with the analog inputs closest to the head. Note that two of the analog 
inputs have been converted to servo outputs to drive the pan and tilt servos. 



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Playful Puppy Robot 




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Playful Puppy Robot 

• Wire the head to the analog inputs so that AO is top, A1 is left, A2 is bottom, A3 is right, A4 
is pan and A5 is tilt. Make sure the white/orange wire from the servos connects to the pin 
closest to the female header. The control wire for the IR LEDs connects to D8. Remove 
the the jumpers for D8 and D10 to isolate the right motor control circuit. 

• Connect your hip and knee servos next. D2 is the rear left hip, D3 is the rear left knee, D4 
is the front left hip, D5 is the front left knee, D6 is the front right knee, D1 1 is the front right 
hip, D12 is the rear right knee and D13 is the rear right hip. Once again have your 
white/orange signal wire closest to the female header. 

• The pan and tilt servos are powered from the 5V regulator as they are connected to the 
analog pins but your legs need more power! 

• The legs can draw about 3A when doing strenuous work so they are connected to the 
battery by two 3A diodes (1N5400). These diodes reduce the battery voltage by about 0.7V 
each and the LiPo has a nominal voltage of 7.4V so the end result is that the servos get 
the 6V they are rated for. One of the diodes is the reverse-polarity protection diode on the 
controller. The second diode we fit in place of the servo power selection jumper. 

• Fortunately for us the legs on a 1N5400 diode are just a tiny bit thicker than a male header 
pin so we can use two short female-to-female jumper wires to connect our diode to the 
PCB without soldering. If you're using NiMH batteries, which are heavier, then you can 
leave this diode out. The servos will be running at 6.6V but this is necessary for the robot 
to stand on its hind legs. 

• Admittedly, when the LiPo is fully charged (8.4V) your servos will get 7V and may get a bit 
hot. If you live in a warm climate and wish to extend the life of your servos then you can 
add a second diode in series giving you 6.3V when the battery is fully charged and 5.3V 
nominal. My robot works fine and the temperature is above 30 °C. 



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Playful Puppy Robot 




• This is an optional step and can be skipped if you wish. 

• I used a short length of spiral wrap to make a tail. I plugged one end with some hot glue 
and then used a self-tapping screw to fix the tail to the back of the robot. I cable-tied a 
small mobile phone vibrator motor to the tail that is driven by the left motor output. The 
sample code feeds more power to the motor as your hand gets closer. 

• You can make your own version of spiral wrap by feeding a drinking straw through a pencil 
sharpener (not the motorized kind). Another alternative is a pipe cleaner from a craft shop. 

• Any small motor can be used make the tail shake. Just mount a small off-center weight 
such as a 6mm (1/4 inch) nut to the motor shaft with some hot glue. 



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Playful Puppy Robot 












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The Magician controller comes preloaded with the Arduino bootloader. If you do not have 
the Arduino software then it can be downloaded for free here . 

The sample code can be downloaded from DAGU's product support site . Go to the 
"Sample Code" page and select "Quad Bot Puppy LiPo" or "Quad Bot Puppy NiMH" 
depending on which batteries you are using. NiMH batteries are heavier so the balance is 
slightly different. 

The program has descriptive comments on most lines and has seperate tabs for constants 
where you can adjust servo center positions and I/O pin definitions. 

Before you can upload the program to the controller you must choose the correct board 
type: "Arduino NG or older w / ATmega8". 

If your computer does not detect the USB serial port then you can download the drivers 
from the DAGU product support site or from Silicon Labs . 

Once the software is installed then you may need to adjust the servo center positions so 
that all hips are at 90 degrees to the body and that the knees are bent inward slightly. The 
photo at the start of these instructions show you how the robot should look after it first 
stands up. If you have problems with your robot then please start a forum on LMR so that I 
and other robot hobbyists can help you. 



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Playful Puppy Robot 





• The robot will happily run around 
following your hand all day but 
there are a few tricks he can 
perform. 

• If you do not play with the robot 
then after 3 seconds it will sit 
down. Once the robot is sitting you 
can bring your hand slowly within 
range. At this point it will follow 
your hand with its head. If you 
move your hand down towards one 
of its front legs slowly then it will 
raise its paw to shake hands. If you 
bring your hand between its paws 
then it will lie down. 

• Once the robot is sitting or lying 
down you will need to bring your 
hand to one side of its head to get 
it to stand up or above its head to 
make it jump up. 

• If you get the robot to look straight 
up then it will try to jump onto its 
back legs. Once on its back legs it 
will still try to follow your hand. If 
you can keep your hand within 
range then the robot will walk on its 
back legs. 



Once the robot is built, install the sample software and have fun. Experiment with the program 
and teach your puppy new tricks. 



This document was last generated on 201 2-11 -01 11 :03:35 PM. 



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